Measurements from satellites this year showed the hole in Earth’s ozone layer that forms over Antarctica each September was the smallest since 1988, scientists from NASA and NOAA announced on November 2, 2017. Scientists pointed to an unstable and warmer Antarctic vortex in 2017 – the stratospheric low pressure system that rotates clockwise in the atmosphere above Antarctica – as the reason.

Ozone is a molecule comprised of three oxygen atoms. A layer of ozone high in the atmosphere surrounds the entire Earth. It protects life on our planet from the harmful effects of the sun’s ultraviolet rays. First detected in 1985, the ozone hole is not technically a hole where no ozone is present, but is instead a region of exceptionally depleted ozone in the stratosphere over the Antarctic. This region of depleted ozone typically begins to appear at the beginning of Southern Hemisphere spring (August–October).

According to NASA, this year’s ozone hole reached its peak extent on September 11, covering an area about two and a half times the size of the United States – 7.6 million square miles in extent – and then declined through the remainder of September and into October.

The 2017 ozone hole was similar in area to one of the earliest ozone holes ever observed – that of 1988 – saidNASA scientists. The 2017 ozone hole was about 1 million miles smaller in extent than the ozone hole of 2016.

Although scientists predict the ozone hole will continue to shrink over time, due to a global human cooperative effort to ban ozone-depleting chemicals, this year’s smaller ozone hole had more to do with weather conditions in Antarctica than human intervention, these scientists said.

CFC11 on the rise...Emissions of Banned Ozone-Eating Chemical Are RisingMay 16, 2018 - Something strange is happening with a now-banned chemical that eats away at Earth's protective ozone layer: Scientists say there's more of it — not less — going into the atmosphere and they don't know where it is coming from.

When a hole in the ozone formed over Antarctica, countries around the world in 1987 agreed to phase out several types of ozone-depleting chemicals called chlorofluorocarbons (CFCs). Production was banned, emissions fell and the hole slowly shrank.

But starting in 2013, emissions of the second most common kind started rising, according to a study in Wednesday's journal Nature . The chemical, called CFC11, was used for making foam, degreasing stains and for refrigeration. "It's the most surprising and unexpected observation I've made in my 27 years" of measurements, said study lead author Stephen Montzka, a research chemist at the National Oceanic and Atmospheric Administration. "Emissions today are about the same as it was nearly 20 years ago," he said.

This image provided by NOAA shows the ozone hole. (NOAA)​

Countries have reported close to zero emissions of the chemical since 2006 but the study found about 14,300 tons (13,000 metric tons) a year has been released since 2013. Some seeps out of foam and buildings and machines, but scientists say what they're seeing is much more than that. Measurements from a dozen monitors around the world suggest the emissions are coming from somewhere around China, Mongolia and the Koreas, according to the study. The chemical can be a byproduct in other chemical manufacturing, but it is supposed to be captured and recycled. Either someone's making the banned compound or it's sloppy byproducts that haven't been reported as required, Montzka said.

An outside expert, Ross Salawitch, an atmospheric scientist at the University of Maryland, is less diplomatic. He calls it "rogue production," adding that if it continues "the recovery of the ozone layer would be threatened." High in the atmosphere, ozone shields Earth from ultraviolet rays that cause skin cancer, crop damage and other problems. Nature removes 2 percent of the CFC11 out of the air each year, so concentrations of the chemical in the atmosphere are still falling, but at a slower rate because of the new emissions, Montzka said. The chemical stays in the air for about 50 years.

Likely cheating on ozone treaty found...Likely cheating on ozone treaty foundFri, May 18, 2018 - CONTRAVENTION: NOAA chemist Stephen Montzka said either the banned chemical is being made or its byproducts are not being reported as required by a 1987 treaty

The decline in the atmosphere of an ozone-depleting chemical banned by the Montreal Protocol has recently slowed by half, suggesting a serious contravention of the 196-nation treaty, researchers said on Wednesday. Measurements at remote sites — including the US government-run Mauna Loa Observatory in Hawaii — of the chemical, known as CFC-11, point to somewhere around China, Mongolia and the Koreas as the source of renewed production. “We show that the rate of decline of atmospheric CFC-11 was constant from 2002 to 2012, and then slowed by about 50 percent after 2012,” an international team of scientists concluded in a study published in the journal Nature. “This evidence strongly suggests increased CFC-11 emissions from eastern Asia after 2012.”

The chemical can be a byproduct in other chemical manufacturing, but it is supposed to be captured and recycled. Either someone’s making the banned compound or it is sloppy byproducts that have not been reported as required, said Stephen Montzka, the study’s lead author and a research chemist at the US National Oceanic and Atmospheric Administration. (NOAA) The ozone layer in the stratosphere, 10km to 40km above Earth’s surface, protects life on the planet from deadly ultraviolet radiation. The 1987 Montreal Protocol banned industrial aerosols such as chlorofluorocarbons (CFCs) that were chemically dissolving ozone, especially above Antarctica.

At its most depleted, around the turn of the 21st century, the ozone layer had declined by about 5 percent. Today, the “hole in the ozone” over the South Pole is showing clear signs of recovery. “The ozone layer remains on track to recovery by mid-century,” the UN Environment Programme (UNEP) said in a statement, reacting to the findings, adding that “continued increase in global CFC-11 emissions will put that progress at risk.” The slowdown in reduction of CFC-11 also has implications for the fight against climate change. “Perhaps even more serious is the role of CFCs as long-lived greenhouse gases,” said Joanna Haigh, a professor at Imperial College London, in commenting on the study.

Two decades ago, CFCs — more potent by far as greenhouse gases than carbon dioxide or methane — accounted for about 10 percent of human-induced global warming. Widely used in 1970s and 1980s as propellant in aerosol sprays, as well as in refrigeration and air conditioning systems, CFCs do not exist in nature. “This is the first time that emissions of one of the three most abundant, long-lived CFCs have increased for a sustained period since production controls took effect in the 1980s,” the study concluded. CFC-11 still contributes about a quarter of all chlorine reaching the stratosphere.

The less rapid decline of CFC-11 could prevent ozone from returning to normal levels, or at least as quickly as hoped, researchers said. “A timely recovery of the stratospheric ozone layer depends on a sustained decline of CFC-11 concentrations,” they wrote. Other scientists not involved in the study signaled its importance. “This is atmospheric detective work at its finest,” said Piers Forester, head of the Priestley International Centre for Climate at the University of Leeds. “The authors pinpoint a new source of CFC-11 to East Asia, breaking Montreal Protocol rules.”